1. Field of the Invention
The invention relates to surface mount technology, and more particularly to a surface mount power supply device and associated method.
2. Description of the Invention Background
Surface mount technology (“SMT”) is the technology associated with a manufacturing process whereby electronic components are mounted and soldered to pads on the surface of a circuit board rather than having their leads inserted into through-holes in the circuit board. SMT has many advantages over the through-hole assembly, including simpler automated manufacturing process, higher density component placement and better miniaturization, greater speed of assembly, etc. One of the limitations of SMT has been component availability. In particular the need for a surface mount DC/DC converter has been identified in U.S. Pat. No. 5,920,461 to Brune (“Brune”). Brune discloses a surface mount power supply device comprising a first printed circuit board, and a lead frame having a plurality of vertically extended pins. One end of each pin is inserted into a corresponding hole drilled on one side of the first printed circuit board, while the other end (the “head”) of each pin provides a surface for electrical connection with a second printed circuit board. In other words, the lead frame is through-hole mounted. The resulting device is still hampered by the disadvantages of the through-hole technology, such as the extra step of drilling holes and matching the pins of the lead frame, and does not fully enjoy the advantages of SMT. Moreover, care must be taken to ensure that coplanarity of the heads of the pins is maintained after reflow, for example by using alignment pins.
U.S. Pat. No. 5,959,842 discloses a surface mount package for containing a board-mounted power supply and associated method. The surface mount package includes a frame that has leads with through-hole mount ends configured to pass through corresponding openings in a circuit board. The frame may include retention clips to retain the frame to the circuit board. All the power supply components are mounted on one side of the board. The package is encapsulated in a shell, and potting material is injected. This surface mount package still relies in through-hole technology and uses a shell and potting material for thermal dissipation.
Other prior-art devices rely on the use of adhesive to hold the lead frame onto a circuit board when components are mounted on both sides of the circuit board by reflow soldering. Using adhesive adds an additional step to the manufacturing process with concomitant cost and time loss. There remains, therefore, a need for an improved surface mount power supply device and method that overcomes the limitations, shortcomings and disadvantages of the prior-art surface mount power supply devices.